There are many areas of technology in which a liquid is contacted with a gas or vapour in a column packed with packing material. Examples of such processes are distillation processes, absorption and desorption processes, gas cleaning and scrubbing processes, liquid cooling processes, gas drying processes and biological processes including biological or percolation filters. Such processes find widespread use in process technology such as in water treatment, particularly effluent treatment, and in process chemistry.
In the past a wide variety of processes of this type have been carried out using packed columns. The number and variety of packings used to pack such columns is very wide. The packing elements may be arranged to form a regular array inside the column or they may be randomly distributed in the column or distributed on some intermediate basis. Random and partially random arrays are usually obtained by dumping a large number of individual small packing elements into the tower.
Numerous examples of dumped packing elements are known from the patent literature, for example those described in German Auslegeschrifts Nos. 1029346 and 1129931, U.S. Pat. No. Re. 27,217, German Pat. No. 316497, U.S. Pat. Nos. 3,266,787, 3,618,910, 2,834,466, 2,602,651, 3,484,513, 3,167,600, 3,311,356, 3,957,931 and 4,041,113 and British Pat. Nos. 768,316, 917,906, 1,385,672 and 1,385,673 and Japanese Utility Model Publication No. 29640/74.
Japanese Utility Model Publication No. 29640/74 discloses the use of packing elements which consist of a deep, short, arcuate trough the base of which has been pressed out to form an oppositely directed bridge.
A number of desiderata apply to elements for use in dumped packings. First of all, the gas/liquid contact efficiency of the packing must be satisfactory for the intended purpose and preferably it should be as efficient as possible. One, though by no means the only, way of enhancing efficiency is to ensure that the packing elements have a high surface area per unit volume of the dumped packing. Another desideratum is that the packing elements should flow easily to form the dumped packing and should not tend when dumped to orient themselves preferentially in any particular way which would have an adverse effect on the performance of the packing. In addition the individual elements should be strong enough that the lowermost elements in a bed of dumped packing elements do not collapse under the weight of the bed above them. A further desirable quality in a dumped packing is that the resistance to gas or vapour flow through the packing should be relatively low.
It is an object of the present invention to provide dumped packings having improved properties relative to previously known packings in one or more of the foregoing respects.